论文标题
剩下的行星撞击形成月球盆地
Formation of Lunar Basins from Impacts of Leftover Planetesimals
论文作者
论文摘要
月亮为太阳系的早期演变提供了重要的线索。在月球表面已经确认了约50个撞击盆地（火山口直径d> 300 km），这意味着早期撞击通量远高于现在。怀疑盆地形成的撞击子是从主带的内部延伸（1.8-2.0 au）释放的小行星。在这里，我们表明，大多数撞击器相反，岩石行星是在陆生星星吸收后留下0.5-1.5 au的岩石行星。剩下的行星的影响预期的盆地数量在很大程度上超过了已知的月球盆地的数量，这表明在月球表面没有记录前200个撞击。在我们的模型中，Imbrium盆地形成（年龄3.92 Gyr;撞击器直径D〜100 km）的概率为15-35％。后来只有两个较小的盆地（Orientale和Schrodinger）形成后，因此必须形成异常迟到。该模型预测20 d> 10 km对地球的影响2.5-3.5 Gy（GA），这与已故的大帝中已知的球形床的数量相当。
The Moon holds important clues to the early evolution of the Solar System. Some 50 impact basins (crater diameter D>300 km) have been recognized on the lunar surface, implying that the early impact flux was much higher than it is now. The basin-forming impactors were suspected to be asteroids released from an inner extension of the main belt (1.8-2.0 au). Here we show that most impactors were instead rocky planetesimals left behind at 0.5-1.5 au after the terrestrial planet accretion. The number of basins expected from impacts of leftover planetesimals largely exceeds the number of known lunar basins, suggesting that the first 200 Myr of impacts is not recorded on the lunar surface. The Imbrium basin formation (age 3.92 Gyr; impactor diameter d~100 km) occurs with a 15-35% probability in our model. Imbrium must have formed unusually late to have only two smaller basins (Orientale and Schrodinger) forming afterwards. The model predicts 20 d>10-km impacts on the Earth 2.5-3.5 Gyr ago (Ga), which is comparable to the number of known spherule beds in the late Archean.
